Carbonation Levels

For this beer, I added enough priming sugar for medium carbonation. That means I expected a reasonable but not excessive amount of gas and head.

Bottle Carbonation Experiment Results

To see the results, I poured all the beers straight into the centre of the glass, aiming for the most head possible.

In an attempt to generate suspense, I’ll go through them in reverse order.

Carbonated 15 Days/In Fridge F0r ½ Day

The beer that had the full fifteen days at room temperature was nicely carbonated with a decent head and a pleasant gassy mouthfeel.

About right in terms of carbonation, although the beer itself needs a bit longer for some of the flavours to settle down.

Carbonated 12 Days/In Fridge For 3 Days

This beer had carbonated too well. It looked like I’d overprimed it.

Carbonated 9 Days/In Fridge For 6 Days

Although with less gas than the first beer, this was still OK and quite nice to drink.

This was the cut-off point I think.

Carbonated 6 Days/In Fridge For 9 Days

Another overprimed one, an anomaly I think rather than a result to later be relied on.

It goes to show how variation from beer to beer is part of home brewing.

Carbonated 3 Days/In Fridge For 12 Days

Just three days of carbonation at warm temperatures gave the beer enough time to develop gas and foam.

However, the head and fizz were short lived.

Carbonated 0 Days/In Fridge For 15 Days

Unappetising and flat, the beer that went straight to the fridge seemed to confirm the theory. Bottle carbonation is best done at room temperature.

Something that hasn’t come through in the photos is the differences in colour. The 0 and 3 day beers were muddy orange/brown, whereas the more carbonated ones were bright and punchy yellow.

I hadn’t expected colour to be affected so much.

Conclusions?

Although it may seem like there’s not a lot of difference, if you look at them all together you can see that the amount of head increases the longer they were carbonating outside the fridge.

Even the longer carbonated of the overly-gassy ones had more foam than its friend.

I’ve always treated two weeks as the minimum carbonation period and this test hasn’t changed my mind on that, even though you could probably get away with less.

The increased staying power of the foam convinced me it’s worth waiting the full fortnight.

There’s nothing particularly surprising about these results. In fact, here’s what the Yeast book says:

The way you store the beer also affects the degree of carbonation. If you store the bottles too cold, the yeast will not actively metabolize sugar and create CO2.

Although it was perhaps inevitable, it’s good to see my assumptions confirmed in reality.

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Comments...

Michael

Hey John, I appreciate your commitment to experimentation. I have been thinking about doing a test to see if there is really any difference in the final product of a wort that has been boiled, and one that has not. I realise the implications for hop scheduling but I reckon I have had some better results dry hopping in the fermenter after a few days of fermentation, compared to boiling the crapper out of a hopped wort. Will also try hopping the mash for bitterness. Be interested to see how you would go if you’re keen. As you can appreciate, not having to boil the wort would be a major time and hassle saver. I guess the main issue would be the sterility of the non-boiled wort, but I’d be willing to give it a go.
Cheers, Michael.

Thanks for the comment and the wild idea. It’d be great if that worked.

I’ve always believed that apart from sanitising the wort, the boil generates hot break (and then cold break when it’s cooled) which helps clear the beer. It also drives off DMS which would taste like boiled vegetables (although I’ve never suffered from that thankfully). I guess this means darker, flavourful beers would be better suited to the technique.

I’m also under the impression that hops have to be boiled in order to contribute bitterness, so perhaps the mash addition alone won’t be enough. Aroma should be much better in the unboiled beer of course.

It’d be easy enough to do a trial batch by siphoning off some wort before carrying on with a regular brew. That’d give you some beer to compare the experiment with.

I’m really intrigued by the idea and have added it to my list of things to try. Do let me know if you have any successes (or otherwise) in the meantime.

I think that was an experiment that was long overdue and thanks for taking the initiative to perform that experiment. You know there is more to this don’t you?
We all want to drink carbonated beer as quickly as possible and maybe you already know the answer to this question. Can you carbonate faster by bottling and increasing the room temperature, say in a fermenter with a controlled atmosphere for a shorter amount of time? How bout that? Do you think it would work?

I think it would work up to a point. I did this experiment in mid-summer with room temperatures around 25°C/77°F. In winter it would seem to make sense to store the beers warm, to mimic these conditions and encourage carbonation.

However, at higher temperatures you may run into similar problems as in the fridge – that is that the yeast stop working. It would be interesting to test this out though.

In any case, even if the carbonation was ready sooner I’ve yet to brew a beer that didn’t taste better after one month in the bottle.

Unfortunately I read Your article after experimenting on my own, but better late than never :) I tested my 1st batch not because I planned to test, but mainly because of available space in fridge and my impatience.

Anyway, my accidental test showed that there was not much difference between 3 days out-1week in; 6 days out – 6 days in and 10 days out – 1 day in. The difference was in taste – the last was the best, I thought this might be because of bottling too early and therefore in needed warmth to finish? And is this also possible that because of this, the carbonating was done equally well (since it was fermenting in bottle more than planned)?

I will make another test soon, when my 2nd batch is ready to be bottled.

Another physical property you touched on here but may not have realized is Henry’s Gas Law. Gas dissolves into solution more readily at lower temperatures. The bottles at warm temperatures have created a CO2 buildup, but the CO2 is not in the beer at that time. Leaving the bottles in the fridge for at least a couple of days will allow the CO2 to dissolve into solution and thus carbonate your beer.

To observe the effects of this, after bottle conditioning the bottles can be put in the fridge. Then each day after you can take one bottle out and observe the carbonation levels, particularly the really little bubbles. I haven’t done this yet, but there should be some difference according to the gas law.